Problem: Solve for $n$ : $-19 + n = 18$
Add $19$ to both sides: $ \begin{eqnarray} \\ -19 + n &=& 18 \\ \\ {+19} && {+19} \end{eqnarray} $ $ \begin{eqnarray} \hphantom{-19 + n} &\hphantom{=}& \hphantom{18} \\ n &=& 18 {+ 19} \\ \end{eqnarray} $ Simplify. $ n = 37$